package lab02.test28;

import java.util.Scanner;

/**
 * Created by MECHREV on 2017/11/5.
 */
public class Test {
    public static void main(String[] args) {
        Double radius;
        Double area;
        Scanner scanner = new Scanner(System.in);
        radius=scanner.nextDouble();
        area=3.14*radius*radius;
        System.out.println(area);

    }
}
